The robotic laser braze/weld has become more popular now in the automotive manufacturing industry due to its precision, low thermal distortion, and efficiency. Many automotive OEMs have started to use robotic laser braze/weld to manufacture car roofs and decklids, especially, for aluminum welding.
Current robotic laser braze/weld tools use a software program to generate process signals such as Command Wire Feed Speed and Start of Wire Feed to a wire feeding device, and process signals such as Command Laser Power and Laser Emission to a laser beam generator. All of these signals are controlled via an Arc Start and an Arc End instruction. The current software does not have adequate signal timing adjustment capability to meet the requirement for the laser braze/weld process. The process is not optimal because process parameters such as the wire feed speed and the laser power are always based on the commanded values specified in the weld schedule and are not adaptive to the actual tool speed, which is typically measured at the Tool Center Point (TCP). As a non-limiting example, when wire feed speed is based on commanded values, it is difficult to synchronize the timing control between the laser power and the wire feed speed during laser power changes.
The robotic laser braze/weld application therefore requires flexible and accurate timing synchronization control for various third party devices and process parameters, such as the laser power, gas flow, wire temperature and wire feed speed, for example. Acceptable laser braze/weld performance further requires adaptive control process parameters. In particular, acceptable laser braze/weld performance requires that process parameters be controlled independently with respect to the actual welding speed.
For example, during corner motion, the actual move speed of the welding tool at a corner region can be substantially slower than the commanded speed. Similarly, during tool beginning and end of motion, as well as during directional changes and during changes in speed, the welding tool is subject to an acceleration or deceleration that causes an actual move speed of the robot welding tool to change. In order to compensate, the weld parameters must be dynamically updated based on the actual weld speed to guarantee laser weld quality. During acceleration or deceleration of the robot welding tool, it is desirable to provide independent ramp control for process parameters based on actual robot acceleration or deceleration at the start or at the end of the laser braze/weld operation. The ability to adapt the braze/weld process parameters to the weld speed is critical in laser applications where the laser can quickly cut a hole in the material being welded or feed more wire than is needed. Without the adaptive capability, the developing, programming, and validating of the weld schedules is tedious, time consuming and difficult.
It would be desirable to provide a laser braze/weld system and method wherein process parameters are controlled independently with respect to the actual welding speed. It would also be desirable to provide a laser braze/weld system and method wherein process parameters are adaptive to the actual tool center point speed.